1. Field of the Invention
This invention relates generally to glazing-and-frame construction and more particularly to fenestration sealed frame, insulating glazing panels.
2. Description of the Prior Art
A conventional window consists of an insulating glass unit supported within a separate frame. Traditionally, the frame was made from wood or metal profiles but increasingly plastic profiles are being substituted made from such materials as polyvinyl chloride (PVC) or pultruded fibreglass.
A traditional insulating glass unit generally consists of two or more glass sheets that are typically separated by a hollow aluminum spacer bar that is filled with desiccant bead material. With a conventional dual-seal unit, thermoplastic polyisobutylene material is applied to the spacer sides and the outward facing channel between the glazing sheets and the spacer is filled with structural thermosetting sealant.
Because of the high thermal conductivity of the aluminum spacer, various efforts have been made in recent years to manufacture the hollow spacer from a rigid low conductive plastic material. U.S. Pat. No. 4,564,540 issued to Davies describes the substitution of a rigid hollow fibreglass pultrusion for the aluminum spacer. Although a substantial development effort was carried out, this product has not yet been successfully commercialized, and technical problems include: moisture wicking at the corners; glass stress breakage, and poor argon gas retention.
One solution to the problem of glass stress breakage to manufacture the spacer from flexible material. U.S. Pat. No. 4,831,799 issued to Glover et al describes a flexible rubber foam spacer that is desiccant filled with pre-applied pressure sensitive adhesive on the spacer sides. This flexible foam spacer has been commercialized under the name of Super Spacer(copyright). In addition to featuring a low conductive spacer, another innovative feature of a Super Spacer(copyright) edge seal is that the traditional roles of the two perimeter seals are reversed. The inner PSA seal is the structural seal while the outer seal is the moisture/gas barrier seal that is typically produced using hot melt butyl sealant.
In the past ten years, other warm-edge technologies have been developed where the traditional aluminum spacer has been replaced by a spacer made from a more insulating material and where there is also a flexible edge seal design. These other warm-edge technologies include: PPG""s Intercept(copyright) and AFG""s Comfort Seal(copyright) product. In total, these flexible warm-edge technologies have now gained about a 80 per cent share of the North American market.
In addition to reducing perimeter heat loss, these new warm edge products also improve the efficiency and the speed of manufacturing the insulating glass units. These system improvements include: manufacturing the edge seal as a metal re-enforced butyl strip (Tremco""s Swiggle Seal(copyright)); roll forming the spacer and incorporating butyl desiccant matrix and an outer butyl sealant (PPG""s Intercept(copyright)); and manufacturing the spacer from EPDM foam with pre-applied butyl sealant and desiccant matrix (AFG""s Comfort Seal(copyright)). Although these improvements allow for the automated production of insulating glass units, residential sash windows still tend to be manufactured using largely manual assembly methods and typically, window frame fabrication is more labor intensive than sealed unit production.
One way of improving window production productivity is to fully integrate frame and sealed unit assembly. In the presentation notes for the talk entitled Extreme Performance Warm-Edge Technology and Integrated IG/Window Productions Systems given at InterGlass Metal ""97, Glover describes a PVC sealed frame window system developed by Meeth Fenester in Germany. With this system, there is one continuous IG/window production line and using an automated four point welder, a PVC window frame is assembled around a double glazed unit. As noted in the paper, some of the concerns with the Meeth system include: problem of broken glass replacement; recycling/disposal of PVC window frames, and the technical risks of no drainage holes.
The present invention provides a fenestration sealed frame insulating glazing panel having an integral generally planar frame that is formed by a number of rigid plastic profiles having interconnected ends that define corners of said frame, said plastic profiles being fabricated in a material that has a low heat conductivity compared to aluminum and a coefficient of expansion that is similar to that of glass; two glazing sheets arranged in spaced parallel relationship and attached to opposite sides of said frame to define therewith a sealed insulating cavity; each framing profile in section having a portion that is overlapped by said sheet, said overlapped portion of each framing profile defining on opposite sides thereof an elongate seat to receive a marginal edge region of a corresponding one of said glazing sheets; each said framing profile having a front face that is located between said elongate seats and is directed into said cavity; said glazing sheets being adhered to said seats by a structural sealant material that exhibits thermosetting properties; a low permeability sealant covering the front face of each of said frame profiles and extending towards the structural sealant on opposite sides of each framing profile to provide a continuous seal between said glazing sheets around the periphery of said cavity.
The low permeability sealant that is exposed to the interior of the cavity can incorporate desiccant material.
Preferably there is a decorative strip provided around the perimeter of each glazing sheet to cover or mask the structural sealant.
The rigid plastic profiles can be provided in many different forms, e.g. as glass fiber pultrusions, oriented thermoplastic profiles, or structural plastic foam profiles. Whatever material is used in these rigid plastic profiles, it should have a heat conductivity that is low compared to aluminum. Preferably the heat conductivity would be less than {fraction (1/100)} that of aluminum. For example whereas the thermal conductivity of aluminum is 160 W/mxc2x0 C., the thermal conductivity of glass fibre is 0.3 W/mxc2x0 C., and that of expanded polystyrene foam is 0.03 W/mxc2x0  C.
A vapor barrier sheet film material can be applied to the front face of each framing profile, and the low permeability sealants may be hot melt butyl or polyisobutylene.
The structural sealant is preferably made from thermosetting silicone material, and an alternative preferred material option is for the structural sealant and the low permeability sealant to be a single material that has both thermoplastic and thermosetting properties, for example in modified silicone material or a modified polyurethane material.
A third glazing sheet can be positioned between the two outer glazing sheets and this third glazing sheet which is the same shape but smaller in size than the outer glazing sheets can either be directly adhered to a stepped frame profile or adhered to either one or both glazing sheets by means of flexible foam spacers.
The fenestration sealed frame insulating glazing panel of the invention may be utilized as a door or a window panel in an exterior building wall. Where the panel is mounted to be moveable, suitable operating devices are attached to the plastic frame for connection to an operating mechanism in the window or door frame in the building wall. When used as a window, the glazing panel is preferably mounted in overlapping relationship to an opening in the wall of the exterior side thereof.
In an alternative configuration the glazing panel in accordance with the invention may be utilized to provide ribbon windows in a building wall. In this arrangement, each panel is positioned so that it spans between top and bottom supports, the side edges of adjacent panels being in abutment but otherwise being unsupported.
The fenestration sealed frame glazing insulating panel of the present invention is self supporting and may be designed to carry structural loads, in this case the glazing sheets being made of laminated glass. In such a stressed skin structural panel, the glazing sheets are preferably spaced apart by at least about 70 mm, and the panel can incorporate a passage through which air can enter and leave the interior cavity, such passage incorporating desiccant to remove moisture from air that enters the cavity between the sheets.